Add Valgrind and ASan to Ex4.

ex4/lecture.md

@@ -12,6 +12,7 @@ The Plan
 ====
 
 * See how GDB works (LLDB on OSX).
+* Look at memory checkers like Valgrind and AddressSanitizer.
 * Cover the quick reference.
 * Debug a program.
 
@@ -27,6 +28,30 @@ Using LLDB
 
 
 
+Using Valgrind
+====
+
+
+
+Using Lint
+====
+
+
+
+Using AddressSanitizer
+====
+
+You neeed clang for this.
+
+
+
+"The Debugger"
+====
+
+When I say "the debugger" in the book I mean to use GDB, but use 
+every tool you can find that helps.
+
+
 
 End Of Lecture 4
 =====